Maybe i didn't explain properly, or understand your question. You pull the chalk out of the plastic holder, put a little piece of cardboard inside the holder, then replace the chalk. Now your chalk is once again higher than the edge of the holder. Again apologies if this is not what your question is.
I have to admit, I see what you mean now. I thought you were saying build up the sides of the holder, which didn't make any sense. Now I see you meant keep raising the level of the interior bottom of the chalk holder to keep the top of the chalk brush-able.
Makes sense. However, in approximately 50 years of playing pool, I've never seen anyone do this. Doesn't mean it can't happen, but I suspect it's pretty rare. I wonder how many people have built up the bottom of their chalk holder with shims to keep their chalk bush-able. The good players I've seen over decades who use their own chalk simply keep track of it.
I don't know, this may qualify for the running of the you've got to be kidding me AZB thread. But I understand your point.